I think it is *highly* individual. Mine are not loud at all. I thought for the longest time maybe it was just because I had utility quality Calls for the most part, but I have added several high quality Calls over the last year to year and half. None of them are loud. Maybe I am just too accustomed to bird noise to notice. I have a couple Call hens that are a little vocal, but certainly nothing that warrants warnings about how loud they are.
What I really tend to think is that loudness is just a trait hat hasn't been selected for in Calls in many generations. That is pretty typical for other breeds as well. People start breeding them for appearance and forget their original utility. It just is what it is. People don't use them for hunting anymore (very often anyway) so, it has just not necessarily been an important trait to preserve. I don't think I have ever heard ANY Call breeder say they can't use a hen for breeding because she is not loud enough, LOL. That is what I mean. It is just not a trait that people select for anymore, hence they are probably not as loud as they used to be.